Quick priming centrifugal pump



Dec. 13, 1966 s. B. M FARLIN 3,291,058

QUICK PRIMING CENTRIFUGAL PUMP Filed April 16, 1965 5 Sheets-Sheet 1 1N VEN TOR.

Dec. 13, 1966 B. M FARLIN 3,291,058

QUICK PRIMING CENTRIFUGAL PUMP Filed April 16, 1965 5 Sheets-Sheet 2 United States Patent 3,291,058 QUECK PRIMHNG CENTRKFUGAL PUMP Stanley R. McFarlin, Jeromesvilie, Ohio, assignor to The German-Krupp Company Filed Apr. 16, 1965. Ser. No. 448,810 18 (Ilaims. (Cl. 103113) This invention relates to self-priming centrifugal pumps and particularly to a new method and to a new system for rapidly and quickly priming a centrifugal pump by repeatedly, and in cycles of about fifteen seconds each, pumping a quantity of liquid from the suction chamber of the pump to the discharge chamber and then returning a similar quantity of liquid from the discharge chamber to the suction chamber.

In conventional self-priming pumps, there is a volume of liquid in both the suction and discharge chambers when the impeller is at rest. The first surge of liquid up in the inlet pipe takes place when the impeller is started and much of the liquid in the suction chamber is pumped into the discharge chamber. Liquid returns continuously to the impeller chamber from the upper part of the discharge chamber while the impeller continues to rotate. Small volumes of gas are entrapped in each such increment of returned liquid and are released when the liquid is in the discharge chamber. Thus, the time required to prime the pump depends on the volume of liquid which is returned to the impeller chamber in any given period of time and the volume of gas which is entrapped therein and transported to the discharge chamber.

While the volume of liquid returned per unit of time will be substantially constant in any given pump, the vol ume of gas entrapped and transported by each such increment of repumped liquid may vary widely depending on the nature and contents of the material to be pumped. More time is required for priming when the vapor pressure of the liquid is low, or the liquid contains detergent foam and the like, both as compared with water. When the priming time is prolonged, the liquid in the pump may be heated to such an extent, or may contain so much foam, that priming cannot be accomplished.

The priming time also depends on the relative sizes of the suction and discharge chambers of the pump for more time is required to prime when the volume of the chamber is small, than when it is large, both as compared'with the volume of the discharge chamber.

The present invention aims to provide much quicker priming with ordinary liquids than has been possible before at slow rotative speeds and substantially high suction lifts with conventional self-priming centrifugal pumps and also to provide for priming with liquids of low vapor pressure or containing foam and the like.

The method phase of the invention achieves those aims by repeatedly, and at short intervals of time, creating a surge of liquid from the suction chamber into the discharge chamber and then returning substantially the same amount of liquid to the suction chamber. Each such surge affords space in the suction chamber into which gas in the inlet pipe may be moved by atmospheric pressure exterted on the liquid outside of the inlet pipe.

Each such movement of gas into the suction chamber is attended by a rise of the liquid in the inlet pipe. Each return of liquid from the discharge chamber sets the stage for the next surge of liquid while each attained level of liquid in the inlet pipe is maintained. When gas is discharged from the suction chamber with each return of liquid to that chamber, the gas in the inlet pipe is removed rapidly and in large increments. Thus, the volume of gas removed from the suction chamber is substantially the same in each of such cycles, does not depend on entrapment of the gas in the returning liquid and the priming time required depends on the volume of gas transferred in each cycle.

The present invention may be carried out most advantageously with pumps having suction chambers of relatively large capacities. The invention is particularly advantageous when liquids of low vapor pressure, or containing foam or the like, are to be pumped for each surge of liquid from the suction chamber is followed by substantially the same distance of rise of liquid in the inlet pipe.

The apparatus phase of this invention achieves the foregoing aim by providing a self-priming pump system with means for repeatedly actuating and deactuating the impeller of the pump in successive predetermined short intervals of time, which means may be operated manually or automatically, and means for discharging gases from the suction chamber of the pump while the impeller is deactuated.

The present invention will be better understood by those skilled in the art from the following specification read in conjunction with the accompanying drawings, in which:

FIGS. 1 and 2 are, respectively, central, vertical, longitudinal and transverse, sectional views of a centrifugal pump which may be employed as part of the present apparatus invention;

FIG. 3 is a perspective view of the diaphragm of the bleed valve of FIG. 1;

FIGS. 4, 5 and 6 are views showing successive stages of the first complete cycle of priming a centrifugal pump by the present method invention.

FIG. 7 is a fragmentary, sectional view of the modified bleed valve of FIG. 4; and,

FIG. 8 is a wiring diagram of a system embodying the present apparatus invention.

FIGS. 1 and 2 show a centrifugal self-priming pump which includes a casing having rear wall 1, front wall 2, partition 3 partly defining a discharge chamber 4 and a suction chamber 5, impeller 6, and rings 7 and 8 forming a part of partition 3 and positioned close to the front surface of the impeller. Shaft 9 is supported in cylinder 10 which has a front part 11 constituting the part of the partition 3 and positioned close to the rear side of the impeller.

Inlet pipe 12 opens into the suction chamber 5 through an opening in front wall 2 which is equipped with a check valve 14. It will be understood that the inlet pipe is to be connected to a pipe (not shown) which extends down into the liquid to be pumped.

A ring 16 is attached to the casing and surrounds an opening 18 through the top wall of the casing and into the discharge chamber 4 and a discharge pipe 20 is screwed into the ring.

Means is provided to control the flow of gases out of the suction chamber under certain operating conditions. The means so shown in FIGS. 1 and 2 includes a pipe line 24 communicating with the discharge chamber 4, a pipe 26 communicating with the suction chamber 5 and a check valve 28 connected to said pipes. That valve comprises two disc-shaped bodies 30 and 32 between which a diaphragm 34 is clamped, as by cap screws 36. The opposed faces of bodies 30 and 32 are cut away to form disc-shaped recesses 38 and 40 separated by the diaphragm 34. The bodies 30 and 32 are provided with threaded bores to receive pipes 24 and 26. The diaphragm 34 is provided with a plurality of holes 46 near the outer periphery of the recesses, as is better shown in FIG. 3.

The operation of check valve 28 is substantially as follows. When the impeller is actuated to pump liquid from the suction chamber into the discharge chamber a vucuum in the suction chamber is thereby created with resultant closing of check valve 28 (or 58). This condition persists so long as the impeller is operating. If,

and when, the impeller is deactuated the liquid in the discharge chamber will flow back to the suction chamber through the impeller with resultant closing of the check valve 14 and opening of check valve 28 (or 58) and with discharge of gas through holes 46 in the diaphragm and pipe 24 (or through pipes 52 and 54) and into the discharge chamber 4. It will be understood that after the pump is primed, the diaphragm 34 will be maintained in its downward position by the vacuum existing in suction chamber 5.

FIG. 7 shows a modified form of check valve. A cover 50 is attached to the top wall of the pump casing and partly defines a chamber 51 which communicates through openings 52 and 54 with the suction and discharge chambers and 4 of the casing having a partition 56. A flapper 58 is clamped between the cap 50 and the top wall of the pump casing and covers opening 52 and is adapted to permit or prevent communication of cham bers 5 and 4 through chamber 51. Preferably, this flapper consists of a body having suflicient rigidity to resist movement into opening 52 under the pressures applied thereto and flexibility enough to be moved away from that opening when the pressure in the discharge chamber 4 is lower than that existing in the suction chamber 5. The operation of the check valve of FIG. 7 is substantially the same as that shown in FIG. 3.

FIGS. 4, 5 and 6 show diagrammatically the successive stages in one cycle of operation of apparatus embodying the present invention. In FIG. 4 the inlet pipe 60 is shown as having no fluid therein except below the level of liquid in tank 61. The pump casing 62 is shown as having liquid at substantially the same level in the suction chamber 64 and in the discharge chamber 66. The impeller is shown at 68. A check valve of the type shown in FIG. 7 connects the suction and discharge chambers above the level of liquid therein. When the impeller 68 is actuated, liquid from the tank rises in the inlet pipe as indicated at 70. During this operation the valve 58 prevents communication between chamber 51 and inlet 52. This condition is shown in FIG. 5.

FIG. 6 shows the next stage of the process which takes place upon the deactuation of impeller 68. Liquid flows through the impeller from discharge chamber 68 into suction chamber 64 until the level of liquid in the two chambers is substantially the same. As the liquid returns to the suction chamber, it closes the inlet check valve 14 but the level in the inlet pipe, as indicated at 70 in FIG. 5, is retained in that position-by virtue of valve 14. As the liquid rises in the suction chamber, gas in the chamber is forced upwardly past flapper 58 and into the discharge chamber. It will be understood that the apparatus of FIGS. l3 operate substantially as just described, the check valve 28 functioning like the flapper 58.

The cycle of operation shown in FIGS. 4, 5 and 6 may be performed in a short period of time, for example, about 5 seconds for the pumping time to go from the conditions in FIG. 4 to that shown in FIG. 5 with a slightly longer time, for example, about ten seconds, for the liquid to return from the discharge chamber to the suction chamber, as represented in FIG. 6.

Pump motor supply and control system FIGURE 8 shows a wiring diagram which may be used as part of the apparatus invention. In that figure a three phase motor 80 is provided for driving the impeller 6. Stator windings (not shown) of the motor 80 are supplied from a three phase supply source at terminals L1-L3 via motor supply conductors 81a-81c. A manually operated main distribution switch 82 and fuses 83a83c are interposed in the pump motor supply conductors 81a-81c between the pump motor 80 and the supply terminals L1-L3.

Normally open contacts Ml-M3 of a main contactor are interposed in the conductors 81a-81c between the pump motor 80 and the main distribution switch 82 to provide for selective energization of the pump motor 80. Overload relay coils 10L and 20L are connected in the motor supply conductors 81a and 81c between the main contacts M1, M3 and the pump motor to detect fault conditions.

A pump motor control circuit 85 is provided for selectively opening and closing the contacts Ml-M3 thereby controlling energization of the pump motor 80 and consequently the pumping action of the pump. The control circuit 85 includes control circuit supply conductors 86, 87 connected to the motor supply conductors 81a and 8111. A control relay branch circuit conductor 88 includes a normally open start switch SW1, a normally closed stop switch SW2, normally closed overload relay contacts 10L1, 20L1 and a control relay coil CR connected in series across the supply conductors 86, 87. A normally open holding contact CR1 is connected across the normally open start switch SW1. A main contactor branch circuit conductor 89 is connected between the supply conductors 86, 87 through the stop switch SW2 and the start switch SW1 or contacts CR1 when closed. The main contactor branch circuit includes a contactor coil M of the main contactor, a normally open contact CR2 which is operated by the control relay CR, a normally closed contact TM1 which is operated by a motor TM of a priming cycle timer, a switch contact FS of a float switch and an Automatic Priming selector contact a of an Automatic Priming-No Priming" selector switch SW3.

A No-Priming contact In is connected by a conductor 90 to the main contactor branch circuit conductor 89 between the timer motor contact TM1 and the control relay contact CR2. The selector switch SW3 is movable from the Automatic Priming contact a to the No Priming contact In so that the coil M may be placed across the supply conductors 86, 87 through the control relay contact CR2, the stop switch SW2 and the start switch SW1 thereby by-passing the float switch FS and the timer contacts TM for operating the pump motor without the automatic self-priming control afforded by the present system. A timer motor circuit conductor 92 includes the motor TM of the priming cycle timer and a normally closed current relay contact 1R1 connected in series between the supply conductor 87 and a point on the conductor 89 between the float switch contact FS and the timer contact TM1. A current transformer 93 is inserted in the supply conductor 81c and provides an output which is indicative of the load current drawn by the pump motor 80. A current relay coil IR is connected across the current transformer 93 and will be energized sufliciently to open its normally closed contact 1R1 whenever the motor 80 is drawing a full load current as when the pump is fully primed and continuously drawing water from the reservoir 61.

The float switch contact FS is operated by a conven-. tional float which is disposed in the reservoir which contains the body of liquid whose level is to govern the operation of the pump. For example, the float may be located in a well or other water source so as to prevent operation of the pump when the water falls to a certain level. Also, the float can be placed into the receiving vessel to turn the pump off when the level within the vessel falls below a second predetermined level. Opening and closing of the float switch contacts FS therefore controls the operation of the pump apart from its primed condition.

The timer motor TM and the timer contact TM1 are part of the priming cycle timer which is to control energization and de-energization of the pump motor 80 for timed ON and OFF periods respectively. The ON period is the time required for the impeller blade to pump substantially all of the water located in the suction chamber into the discharge chamber. The OFF period is the time required for the water which has been pumped into the discharge chamber to flow into the suction chamber to establish an equilibrium with the check valve permitting venting from the suction chamber into the discharge chamber.

In practice with the pump shown in the drawings, an ON time of 5 seconds and an OFF time of seconds has been found to provide a satisfactory priming cycle. In a preferred form of the timer, the contacts TMl are actuated by a cam (indicated by broken lines 95) which is rotated by the armature of the motor TM to close and open the contacts for the ON and OFF periods selected.

When the pump is ready for priming, it contains a quantity of liquid in the suction and discharge chambers somewhat as indicated in FIG. 4.

The selector switch SW3 is then positioned to the Automatic Priming contact a to provide automatic self-priming of the pump. The main distribution switch 82 is closed to connect the main supply conductors 81a 81c across the voltage supply source Ll-L3 and consequently energize the control circuit supply conductors 86, 87. The start switch SW1 is pressed to energize the control relay coil CR across the supply conductors 86, 87 through the normally closed overload contacts 10L L1, the stop switch SW2 and the start switch SW1. The energized control relay coil CR closes its normally open contact CR1 and CR2. The closed contact CR1 makes a holding circuit across the start switch SW1 to maintain the control relay coil CR energized after the start switch SW1 is released. The closed contact CR2 sets up the main contactor branch circuit conductor 89 for energization of the main contactor coil whenever the float switch contact FS closes. Closure of the float switch contact PS causes energization of the contactor coil M provided the timer contactor TMl is closed.

The energized contactor coil M closes its normally open contacts M1-M3 to energize the windings of the pump motor 80. The pump motor starts rotating the impeller and pumps liquid from the suction chamber into the discharge chamber, thus creating a partial vacuum on the suction side of the pump. Atmospheric pressure exerted on the liquid to be pumped forces liquid up in inlet pipe 60, the height to which the liquid is lifted depending upon the volume of liquid pumped out of the suction chamber of the pump and the interior dimension of the pipe 60. In some applications, the liquid may rise some 4 to 5 feet up the pipe 60 each time the liquid is pumped out of the suction chamber. FIGURE 5 illustrates the conditions existing at the end of the first pumping cycle.

The timer contact TMl maintains the contactor coil M energized and, consequently, the pump motor 80 energized for the ON period which is pre-set to the length of time necessary to transfer substantially all of the liquid from the suction chamber to the discharge chamber, i.e, 5 seconds in the system shown. At the end of the timed ON period, the timermotor TM opens the timer contact TM to cause de-energization of the main contactor coil M and consequently de-energization of the pump motor 80 when the main contacts M1M3 open. The impeller stops rotating and the liquid in the discharge chamber 66 is allowed to flow back into the suction chamber 64 until the equilibrium condition is again reached. The timer motor TM maintains the contacts TMl open for this OFF period which is pre-set to the amount of time required for the liquid in the discharge and suction chambers to reach. the equilibrium position, i.e., 10 seconds in the system shown. The check valve 14 maintain the vacuum within the pipe 60 to maintain the level of water 70 and to prevent the flow of liquid from within the pump casing back into the pipe 60. The check valve 28 permits the air within the pump suction chamber to vent across into the top of the discharge chamber. This point in the priming cycle is illustrated in FIGURE 6.

The timer motor TM is continuously running and at the end of the OFF period again closes the timer contacts TMl. The closed contacts TMl again energize the main contactor coil M which closes its contacts Ml-MS to energize the pump motor 86 to initiate another priming cycle. The timing motor continues to run for several consecutive ON and OFF periods causing several priming cycles, each of which lifts the liquid in the pipe substantially equal predetermined amounts. The priming cycles continue until the entire pipe 60 and the suction chambers are substantially filled and the pump is substantially fully primed. When the pump approaches a fully primed condition, the load on the pump motor increases to a point where the motor is operating at substantially a full load condition during the ON period. When the pump motor reaches this fully loaded condition, the current in the motor supply conductor 810 increases to a point which sufficiently energizes the current relay coil IR to open its normally closed contact 1R1. The opening of the current relay contact 1R1 de-energizes the timer motor TM so that the timer contact TM remains in its closed position to maintain the contactor coil M energized and consequently the pump motor 80 continuously running.

When the level of liquid detected by the float switch is such as to open the float switch control PS, the contactor coil M is de-energized and consequently opens its contacts M1-M3 to de-energize the pump motor and stop the pumping action. Should the liquid level change such that the contacts FS again close while the pump is still fully primed, then the motor is initially under a full load operating condition and draws sufficient current to energize the current relay coil IR to open its contact IRll and maintain the timer motor TM de-energized. In this condition, no priming cycle occurs. If the pump loses its prime, prior to closure of the float switch contact PS, then the load current drawn by the motor is not sufficient to cause the current relay coil IR to open its contacts 1R1 and the timer motor TM is energized upon closure of the float switch contact PS to start another series of priming cycles.

Should the float switch contact PS close when the timer motor contacts TMl are not closed, then the timer motor TM will be energized through the control relay contacts CR1 and the stop switch SW1. The timer motor will rotate and subsequently close the contacts TM]. to start the automatic priming operation.

In some instances it may be desirable or necessary to prime the pump manually. This is accomplished by moving the selected switch SW3 to the contact In which by-passes the timer motor contact TMl and the float switch contact FS. Operation of the start switch SW1 and the stop switch SW2 directly controls energization and de-energization of the pump motor 80, respectively. Alternate manipulation of the switches SW1, SW2, first operating the start switch SW1 and then the stop SW2 with appropriate pauses to provide the above described ON and OFF periods will cause the liquid to advance up the pipe 60 until complete priming is achieved. The duration of the ON and OFF periods may be timed or they may be determined by noting changes in the operation of the pump as by chamber pressure gauges, motor current meters or sensing changes in operating noise of the pump. Complete priming is detected by noting a continuous or non-changing characteristic of the pump operation as well as noting an increased continuous load on the motor 80.

Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated of carrying out this invention, I state that the subject matter which I regard as being my invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above specifically described embodiment of the invention may be made without departing from the scope of the invention as set forth in What is claimed.

What is claimed is:

1. The method of priming a self-priming centrifugal pump which comprises the steps of moving a quantity of liquid from the suction chamber of the pump into its discharge chamber, thereby causing liquid to rise in the inlet pipe of the pump, and then allowing approximately the same quantity of liquid to return from the discharge chamber of the pump into its suction chamber while maintaining the liquid in substantially its attained position in the inlet pipe and repeating said steps in sequence until the inlet pipe and suction chamber are filled with liquid.

2. The method of priming a self-priming centrifugal pump which comprises the steps of moving a quantity of liquid from the suction chamber of the pump into its discharge chamber, thereby causing liquid to rise in the inlet pipe of the pump, and then allowing approximately the same quantity of liquid to return from the discharge chamber of the pump into its suction chamber while removing gas from the suction chamber and while maintaining the liquid in substantially its attained position in the inlet pipe and repeating said steps in sequence until the inlet pipe and suction chamber are filled with liquid.

3. The combination of steps set forth in claim 2 in which the gas removed from the suction chamber is led into the discharge chamber.

4. The combination of steps set forth in claim 1 in which several cycles of the said steps are carried out in about one minute.

5. The method of priming a self-priming centrifugal pump which comprises the steps of pumping a quantity of liquid from the suction chamber of the pump into its discharge chamber in a few seconds by actuating the impeller thereby causing liquid to rise in the inlet pipe of the pump, and then allowing substantially the same quantity of liquid to return from the discharge chamber into the suction chamber in a slightly longer time by deactuating said impeller while maintaining the liquid in substantially its attained position in the inlet pipe.

6. The combination of steps set out in claim 5 in which the gas is discharged from the suction chamber while the liquid is returning thereto.

7. The combination of steps set forth in claim 6 in which the gas discharged from the suction chamber is led into the discharge chamber.

8. The combination of steps set forth in which the actuation and deactuation of the manually controlled.

9. The combination of steps set forth in which the actuation and deactuation of the automatically controlled.

10. The combination of steps set forth in which the actuation and deactuation of the manually controlled.

11. The combination of steps set forth in which the actuation and deactuation of the automatically controlled.

12. A centrifugal pump system comprising a selfpriming centrifugal pump having suction and discharge chambers, an impeller, an inlet pipe, a valve to check back flow of liquid in said pipe, motor means to actuate said impeller, control means to actuate and deactuate said motor means, and means to bleed gas from said suction chamber while the impeller is deactuated.

13. The combination of elements set forth in claim 12 in which the gas bleeding means includes a pipe connecting the suction chamber and a check valve.

14. The combination of elements set forth in claim 13 in which the gas bleeding means includes a pipe connecting said check valve with the discharge chamber.

15. The combination of elements set forth in claim 12 in which the control means is manually controlled.

16. The combination of elements set forth in claim 12 in which the control means is automatically operated.

17. The combination of elements set forth in claim 16 in which the said automatically operated means includes electrical means responsive to the power supplied to the motor means.

18. The combination of elements set forth in claim 17 in which the said electrical means includes a transformer and a timer controlled by current flow to said motor means.

claim 5 in impeller is claim 5 in impeller is claim 7 in impeller is claim 7 in impeller is References Cited by the Examiner UNITED STATES PATENTS 1,488,449 3/1924 Burkhardt 103-113 1,513,705 10/1924 Haentjens 103-113 1,563,337 12/1925 Caputo 103-113 1,995,812 3/1935 Noble 103-113 2,672,818 3/1954 Adams et al. 103-25 2,705,456 4/1955 Heyman 103-25 MARK NEWMAN, Primary Examiner.

H. F. RADUAZO, Assistant Examiner. 

1. THE METHOD OF PRIMING A SELF-PRIMING CENTRIFUGAL PUMP WHICH COMPRISES THE STEPS OF MOVING A QUANTITY OF LIQUID FROM THE SUCTION CHAMBER OF THE PUMP INTO ITS DISCHARGE CHAMBER, THEREBY CAUSING LIQUID TO RISE IN THE INLET PIPE OF THE PUMP, AND THEN ALLOWING APPROXIMATELY THE SAME QUANTITY OF LIQUID INTO ITS SECTION CHAMBER WHILE CHAMBER OF THE PUMP INTO ITS SECTION CHAMBER WHILE MAINTAINING THE LIQUID IN SUBSTANTIALLY ITS ATTAINED POSITION IN THE INLET PIPE AND REPEATING SAID STEPS IN SEQUENCE UNTIL THE INLET PIPE AND SECTION CHAMBER ARE FILLED WITH LIQUID.
 12. A CENTRIFUGAL PUMP SYSTEM COMPRISING A SELFPRIMING CENTRIFUGAL PUMP HAVING SUCTION AND DISCHARGE CHAMBERS, AN IMPELLER, AN INLET PIPE, A VALVE TO CHECK BACK FLOW OF LIQUID IN SAID PIPE, MOTOR MEANS TO ACTUATE SAID IMPELLER, CONTROL MEANS TO ACTUATE AND DEACTUATE SAID MOTOR MEANS, AND MEANS TO BLEED GAS FROM SAID SUCTION CHAMBER WHILE THE IMPELLER IS DEACTUATED. 